SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82a207fb04bb823765f95dfd1f41ead6723b74ff14d0da7fa38b967a8506b1b7' 
  AND token = '21QkkrYtxZo21dUCTKjr11JId5Qkxo4EAjSuQ6/z7PY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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