SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f8ce601a94e6f7a7bc9585a5db258fc3ab3cac552f8f47122703432966e29ae' 
  AND token = '4+gYXLveZreMNwFTqFQc5CG/Om7tWFSKnx5PsOuFL5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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