SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3d07406248f9b5aaa832625a07ea95dde9a89701187458dd09e96d875b2bb51' 
  AND token = 'xNzyUCWJ9YjleEFx2V6+bhheqrVuYfsoc4DYMBS9Dh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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