SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a6ae0214f52123985b433b30cfe6ac236d424ecf78916d256e4f8ff3d6f3cb62' 
  AND token = 'iGUQe4gh6dODEGzSaLk6LHA7TECV7pCeL2JRXGZIdZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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