SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '616fcc2a107321ec1ef3de30b8693742acd1ea1e2064d629427fae743520fe21' 
  AND token = 'AV19LycRJIge9ZNE0wd6iOwU/3ZzoAaO5xV0pebwEkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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