SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28679b8cd41090a7855be6615c87641332ad82b2744138d2a67519a4561c31a8' 
  AND token = 'q0vS3pZmK6gAsZ5oRQQVfLVXlNaJspVPAceI1tGW6qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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