SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cba8fb356433aa1261582b1da012bf9a6ca348ec0e169032f8b6dabf50d92ca6' 
  AND token = '+KOHLiJP1Gmv5VMxhXBi+e/+dWvAeXvGqjI94ZnBPBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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