SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b656209630ed1796c00a3dbab0d654d5e479f5286d0419171897be349b50634' 
  AND token = 'CN9Gena8ZIn7c/YJntrYJsiY3JBokoip7ozlX3NRKig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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