SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391b1b9b8d98224e2a30ebcec7a8ba7dd041465fdd5a38d213fc37ecad605bf6' 
  AND token = 'lepSlvksF/bUgAhnJBEPgeKIKAZaPfeGB/RPyzyj+VI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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