SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9968be45d17a600409ad53cae68c6078562ac71db11e4588441d4aece290bc9f' 
  AND token = 'GwK6EROqBk+GYIC8SWjyvLhl0z7ymFt1Uqvumb5RI7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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