SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14ae34a76a901461f803d63b70a9d07fa3c0b34644dc9f75b54fadba5043a383' 
  AND token = 'x6JzUYp8wETXThIQB5T8bRFXnjQuL5lB+g6W5BoCHRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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