SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8ea09062fa72c2d5e1cd270746f97e0e86b4a3a961b9c2b47f124a57dbec213' 
  AND token = '5LP/GU6abCPw/1ghFzQfnPQiZULSOvxkYl/mZDrVl+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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