SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0305375812ba8beecfe46e264c0942b95a88271a57b8fd3de2c1f5d31dac586' 
  AND token = 'YSzjuST8OlFgZ4EURm8u2VCwf1Hy09wXO/tSN9f+m44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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