SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78a37c7850b20bd8ccd11859e6129f087306dbcbd688e58d8aba62fce9598832' 
  AND token = '/kFsntBfYdFZjzg2J3V6oFBEjBcP0jraLPhoJ6um4vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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