SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae42ad3e8e6e21041e63adda320a8c91c5e22027317d10add3ab60c35a8a4a93' 
  AND token = 'R5kLMFtkfHmmFcwJMkbNRsRkrIVKvYjq6J16oS4/grM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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