SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '5b5472d2d3000853e771632da89b7378920be1ab428a9db193daf3cd1333c788' 
  AND token = 'IOUJv7meHWQvxAuaV0qeqnAwiyVH1ETzBSdZoDjRNFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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