SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d20ee274f7787571d78350565b34692532207797a68c585c64e263c5cfb122' 
  AND token = 'x3PJUrT/EUjhBNkP6xGd/xoAXiVE0OH0yiDf7HVlz/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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