SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '970b0673ce60d4857939126256fdb785d108190152b58e584cc2dd17ab2fcd03' 
  AND token = 'clzBut4hK26kXSa1AHyaPMDrBBjndd7qtwb5maL+KVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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