SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7020603916cdf1edae661a26f1c14b07eaec73f064f9891242fa5e015811e4' 
  AND token = '92docE9o0UFd8gjIMF3IorIDfijTFfEt8tN3OLFTyx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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