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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2a4b97a0a72bf4496dbad87b982226f6a25c5b4a3375c4862ee3032a82786a8' 
  AND token = 'Y9v/8AXiNv3KbWsD2IRim8uzjFw6v3j6Vql9Vuq72G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}