SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03c520870fbe7f6c22133867368cc4d96eb81e4de67d8485d9d08c06fbb29420' 
  AND token = 'PAwq5Z9qmyl/mvJ++HGv52qLpdsiwF7mGvt1oJ815X4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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