SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7875f5ff9272824102563aa13745f95c95a36dfa4bf8f1a88779810b2c93f25' 
  AND token = 'idQyoyhKUNLv/xnE8RBgaCVqv6a7ekzxdkjawKGnD00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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