SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c29f5b9469cdefdfffd3855d92e1e832351c02789426f10e4eef880d9342b6e3' 
  AND token = 'tT2KT7XLDlfCrhI9fTXM+V08vRNunZplTm36JXoXvfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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