SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5a22942175df62668267ca39291c34f70ea07554657ad33e3535b947a48bac8' 
  AND token = 'JW4IpBM36QaZlBSncCIsenSY7ddriN2JaCRvrLA4BBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}