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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7e3e4a4fdfc8d4d9b6f6c37fcc18af9003ddbd16ef039040bc1f747ae6d9936' 
  AND token = 'etgDJnx6ffBkQrlT1c7DXklyEV9TZddNxvoT14KwkQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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