SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6023ea2103ebc601162f81f980c610a1ad75be2ccc3bffabbd035b16ea6ca8fe' 
  AND token = 'ouupDguBgC3qMbwieGIOXDF+nNci71aoFsFAVpDT3W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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