SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a912be7d0da45c4b36a7e985314226e24a6219c7fdead9d83d37028981290ec' 
  AND token = 'UFqlulCLDkvIybKkp52q/E21G+0X7EiEmUgRBJUQwOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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