SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b94c5124aff66f84572425412722cd66e80d60f1d0f24a35dcc2f680e7e533c0' 
  AND token = 'G/sBokJEIcYsqwvFJzdxx/1lSr9aN64AXsTOiQqUQDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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