SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ae14812fd152b84a3e1b7103190a8731608680118052b221e562b7a157d6042' 
  AND token = 'kSQCtnsB+XOo69uCdbaMhG8U7XUCxClwg+TZ5Qlztu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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