SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e975367bb8977a0b220b143a119cf04da8265fdb298d9e2a65601d4a0a7cd9a6' 
  AND token = 'vCBIsTZXZY2llVLKF9dGVpx1hkwaxce6urlMQRcXI+4=' 
  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"
    }
  }
}