SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3a6a708a354fe0e602738dc66ac1e2e00615f84268ccef61e7208bc2af67e91' 
  AND token = 'pnkQtu/KYbISdNrttEmUhciDgZhsVCSBAAEsRFMl05k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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