SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '434f44c92d147e088fbd78569ec241c67653a38e2e4955deced5dfe35bb366f0' 
  AND token = '9Lm2nC3Igy7Z3xw6YvuOmlaeSnKphDrPj/UyWH3KsZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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