SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dcbf231e7daf4c420e45770b33ad732d9878c0d35763c82c06b4566bcef4545' 
  AND token = 'ATwtxouDv9FBmVRvOM16TkyIoW6nNAPixR8zyUsamsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}