SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49f18b85d5ae5603a61def81ddc83ef5e7e523dbc868da4645d8128896c6a65d' 
  AND token = 'Q/4WSfOFrBZyqTZDTcKbZTG0IvceI8ZTo91AxMDSOws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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