SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68bfa9b5e4cae144819e90f95d7aea33fad47f6ace6ad53be5cec2fa54992782' 
  AND token = 'xyE4jW27gnbE4QvAlY63Qvi6DBcuL6g7b+Xa0zbYRas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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