SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab029fc7d47deec4a1981f0c39e2f92e32a4d46559e9038668d544127c03e2b' 
  AND token = 'nP+9GpmTFAvsvWCuJ8oTjgNXogFO8hwNBEnu4N8Ys20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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