SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '737ca79d34698d9950c73ecf41d7d3620d167eadb84cb453d5a90faec9814a12' 
  AND token = 'nKls0OjF8IvhV61L+v2mJptCgw5r4IMkHCfzcGIti/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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