SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8159286507edb878fee784b6920130c054fd92f5e78a183a30a4a3c52d3fc58' 
  AND token = '3CUVWnJNmK+HALPQS4yyTr+/GMQ4hDFY7dccwaveJ6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00102

JSON explain

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