SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e888868c83442f468c1985e604c1993fdc07b6e2fe7f8c0c3e0593fbf91edad' 
  AND token = 'INiH6CX3UGiRDIbangPVUX10pIm+YPpJi8DnqhZzeZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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