SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820d94488cf4d8d280de04479f0a83b8f9d19a2ae62c736a78c9df560fe75bba' 
  AND token = 'QKyTI3m4VWmdA81XSlwUqLbbcIBm2J1cxbOoEPU37Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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