SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be5f5b514b6bf80626fc5638d05213b450aaa659166fc2841625b59926fd520b' 
  AND token = 'gaUjze5Qv0vfYJRehzDi6NZvzSHicS27EYFlNyNdMA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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