SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd4390f2068432900eeee9a2feda1ea2ce50dc2024d07915a2e102552235000b' 
  AND token = 'vrcPO9KneiymuLSqwFeTllv9QyNq/R24z+xsCKdElKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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