SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75a91a808b0b0f5859715f9fd494cde6d030f312f02bf3da19277158fcc87684' 
  AND token = 'mUL8ntA6XmHr0yY6SHnw0t9XnZyGaw29hRRwraw35CA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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