SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74d87793625b76c14e822a5c168c6e94fade5d713e15f2c84e9b4dc6987b6bf7' 
  AND token = 'ECwixF7rb93l7PQ6lEdFWzAkwNdJBhrzwPhGIMY9vs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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