SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b5552ea5cf05c4e0de0ab9145bb618f22517b64dd84a797887be386de1bb40c' 
  AND token = 'y8HZGrSv6qp3Kf2lxGMkR6e9udaJgjVgGQDWuhqPiGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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