SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3550697581d5d2d20365bb44a32246495eb3e7a76a9819e6d61ae99cf8fd0c08' 
  AND token = 'aFI6CmiBFZkTGoCYQdLOW2jrsbBD5vvMq9WPj1ReZgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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