SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f5e8bac07d677e91fa0e709750f4d618348e8f20edb09f304552ec4a997120' 
  AND token = 'BZBeP7Jn1/8AGX3XgYfdvSpRTNNQZW1wZHPljTsu/hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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