SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e21150b6ace91a8eef05de987ad160e1799cd649566c34f7c4cb0b31faf45f2e' 
  AND token = 'sDlDh2+izvgJWEbb4XzhEcGtQHvAG6wI1YSGvLHBIKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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