SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd874ffda0fcc11520f47b8ed9e9e15462d2c2dd70953313944a5a08c7772bf46' 
  AND token = 'PMROFcQ5rxoYQwzgJAusIJsjJCLulwsuLURHYYBMb/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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