SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52aa8945bd88041320938af117aaaaedcec0a0768ddc09d97ecf92fe961b72c5' 
  AND token = 'BYRyQpmKx8jl4ZtMhlX8Hy51dXzfuQZUQaPW0AeAQ5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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