SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b3dc1945b1918cf7503cf96b4318ac2bbab18349fc749f575b62d57ce5cef7' 
  AND token = 'etBXiXh+LlW+vSMwIQD1NFzR2urhoGeFmtGZOjJ5T8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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