SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4dceaefbf8784e15fbe11f8fc54a6b151263f7177f50945c8cc26d3268aa6d9' 
  AND token = 'WfgtRBsO7EWxH+D1o4Bqfvdc5IJCRBiUHXG6vwhsgMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}