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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7b248f2377506a66a4eda25440155de2ba9f0ebd73d602acbda8552673e98e8' 
  AND token = 'AHdE5aAWl+h7Zw0fJ8rBBbz2NtaiUfcSQMVIvOy5Oyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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