SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eb48f233616e50efa3a411b25792292e5d8cd0b85468ba017e80f974e87e7b9' 
  AND token = 'K6MfdSMMHGmBuL+qpmlB7R8t2P9crDuw+GcKK5jF8rU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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