SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '666b875af875b04948da6df892a3ec5716436b19c463380db48fdd321b84732b' 
  AND token = '8M43kRJczcdgZ/cEAcpGZGmzTrBhny2MZXRrrJ7T5s0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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