SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af821dac10e2cd75d010869166c4460fe7338cb091c5debf4884474e08dc8fef' 
  AND token = 'YAQsENlVHtBvuMKmJpK5BnaUj9mr4d+MNsJhpMgPhcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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