SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50fc2865f14026c98daf150f754c07eadd0a0b270ffb17763032e98d8b3f064' 
  AND token = 'vOZYkWWhIjCkCWsIx54j3rNxETJYoP55pVSQ23vIo4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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