SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15a86af9c8279af6e1e8dcf54f8abe9016bee7d07a93b224b18d55f416428256' 
  AND token = 'wl1odAoeEqDsCdtZZRcstsEIJyBiVHOmHoK77Sk00Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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