SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c90aa108a91728da8692726523ce974dda3e43d575372e2d68d558bcb6ee632' 
  AND token = 'UbLVeEJygge5rLl5ZjoIrWgVKZ/RrRUh1bamxiMmEEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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