SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1553975479ba529f0ff83c9c4bcfce6959519bcf5d1dace9a4a9173d1e66647f' 
  AND token = 'T2Cq5XRg+FxumzJSgsPFmqFb81VExBLhdHN9u+TSUBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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