SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d85f498870044b26fefcedf72a798318dba76d079778e494a5ecd6119d205c' 
  AND token = 'HYvbnUYZj2sRiclKIXmLvJ+B6+nb4GMQ8Cd2H1Nrj7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}