SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3e8db4867a980a709a032fb67991160570be351af2545149848104460f3f234' 
  AND token = 'BLAVJm7BnUvtqmw/sIjiGK+FsKo3txMKZupf3y7q3gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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