SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b777faf700aa7f975242f9b70e20f332634c491b89b60805b28870a6f1fb22ec' 
  AND token = 'YBrqvKol1Z70MUqp+piXlrgJ/ehjrlq5mY2QnuuoLv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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